Heat-pump using apparatus

ABSTRACT

A heat-pump using apparatus includes a refrigerant circuit, a heat medium circuit, and a heat exchanger which causes heat exchange to be performed between refrigerant and a heat medium. A main circuit of the heat medium circuit includes a branching part and a joining part. To the main circuit, a pressure protection device and a refrigerant leakage detecting device are connected. The pressure protection device is connected to a connection part located between the heat exchanger and one of the branching part and the joining part in the main circuit. The refrigerant circuit includes a first blocking device and a second blocking device between which the heat exchanger is located.

TECHNICAL FIELD

The present invention relates to a heat-pump using apparatus including a refrigerant circuit and a heat medium circuit.

BACKGROUND ART

Patent Literature 1 describes an outdoor unit of a heat-pump cycle apparatus using flammable refrigerant. The outdoor unit includes a refrigerant circuit in which a compressor, an air heat exchanger, an expansion device and a water heat exchanger are connected by pipes, and a pressure relief valve which prevents an excessive increase in hydraulic pressure in a water circuit for supplying water heated by the water heat exchanger. Thereby, even if a partition wall which isolates the refrigerant circuit and the water circuit from each other in the water heat exchanger is broken, and the flammable refrigerant thus enters the water circuit, the flammable refrigerant can be discharged to the outdoors via the pressure relief valve.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2013-167398

SUMMARY OF INVENTION Technical Problem

In a heat-pump using apparatus such as a heat-pump cycle apparatus, in general, a pressure relief valve of a water circuit is provided in an indoor unit. In the heat-pump using apparatus, there are various combinations of outdoor and indoor units. For example, in a given case, an outdoor unit and an indoor unit manufactured by the same manufacturer are combined together, and in another case, an outdoor unit and an indoor unit manufactured by different manufacturers are combined. Therefore, the outdoor unit described in Patent Literature 1 may be combined with an indoor unit equipped with a pressure relief valve.

However, in the above case, if refrigerant leaks into the water circuit, refrigerant which mixes with water in the water circuit may be discharged not only from a pressure relief valve provided in the outdoor unit, but from a pressure relief valve disposed in the indoor unit. Therefore, there is a risk that the refrigerant will leak from the water circuit into a room.

The present invention aims to solve the above problem, and provide a heat-pump using apparatus which can prevent leaking refrigerant from entering a room.

Solution to Problem

A heat-pump using apparatus according to an embodiment of the present invention includes a refrigerant circuit which circulates refrigerant; a heat medium circuit which causes a heat medium to flow therein; and a heat exchanger which causes heat exchange to be performed between the refrigerant and the heat medium. The heat medium circuit includes a main circuit extending via the heat exchanger. The main circuit includes a branching part which is located at a downstream end of the main circuit, and connected to those portions of a plurality of branch circuits which branch off from the main circuit are connected, the branching part being provided at a downstream end of the main circuit, and a joining part which is located at an upstream end of the main circuit, and connected to those portions of the plurality of branch which join the main circuit. To the main circuit, a pressure protection device and a refrigerant leakage detecting device are connected. The main circuit includes a first blocking device and a second blocking device between which the heat exchanger is located.

Advantageous Effects of Invention

According to an embodiment of the present invention, even in the case where refrigerant leaks into a heat medium circuit, the flow of the refrigerant in a refrigerant circuit can be blocked by a first blocking device and a second blocking device. It is therefore possible to reduce leakage of refrigerant from a pressure protection device into indoor space.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a circuit diagram illustrating a schematic configuration of a heat-pump using apparatus according to embodiment 1 of the present invention.

FIG. 2 is a circuit diagram illustrating a schematic configuration of a heat-pump using apparatus according to a modification of embodiment 1 of the present invention.

FIG. 3 is an explanatory diagram illustrating examples of the position of a refrigerant leakage detecting device 98 in the heat-pump using apparatus according to embodiment 1 of the present invention.

FIG. 4 is a circuit diagram illustrating a schematic configuration of a heat-pump using apparatus according to embodiment 2 of the present invention.

DESCRIPTION OF EMBODIMENTS Embodiment 1

A heat-pump using apparatus according to embodiment 1 of the present invention will be described. FIG. 1 is a circuit diagram illustrating a schematic configuration of the heat-pump using apparatus according to embodiment 1. In embodiment 1, a heat-pump hot-water supply heating apparatus 1000 is provided as an example of the heat-pump using apparatus. In figures including FIG. 1 which are to be referred to below, the relationships in size, shape, etc. between structural components may be different from actual ones.

As illustrated in FIG. 1, the heat-pump hot-water supply heating apparatus 1000 includes a refrigerant circuit 110 in which refrigerant is circulated and a water circuit 210 in which water is made to flow. The heat-pump hot-water supply heating apparatus 1000 further includes an outdoor unit 100 installed outside an indoor space (outdoors, for example) and an indoor unit 200 installed in the indoor space. The indoor unit 200 is installed in, for example, a kitchen, a bathroom, a laundry room, or a storage space such as a closet in a building.

In the refrigerant circuit 110, a compressor 3, a refrigerant flow switching device 4, a load-side heat exchanger 2, a pressure-reducing device 6 and a heat-source-side heat exchanger 1 are successively connected by refrigerant pipes. The refrigerant circuit 110 of the heat-pump hot-water supply heating apparatus 1000 is capable of performing a normal operation (for example, a heating and hot-water supplying operation) in which water flowing in the water circuit 210 is heated and a defrosting operation in which refrigerant is caused to flow in an opposite direction to the flow direction of the refrigerant in the normal operation to defrost the heat-source-side heat exchanger 1.

The compressor 3 is a fluid machine which compresses low-pressure refrigerant sucked therein, and discharges the refrigerant as high-pressure refrigerant. In this embodiment, the compressor 3 includes, for example, an inverter device, and can vary a capacity (the amount of refrigerant to be sent unit time) by arbitrarily changing a driving frequency.

The refrigerant flow switching device 4 switches the flow direction of the refrigerant in the refrigerant circuit 110 between that in the normal operation and that in the defrosting operation. For example, a four-way valve is used as the refrigerant flow switching device 4.

The load-side heat exchanger 2 is a water-refrigerant heat exchanger which causes heat exchange to be performed between refrigerant flowing in the refrigerant circuit 110 and water flowing in the water circuit 210. For example, a plate heat exchanger is used as the load-side heat exchanger 2. The load-side heat exchanger 2 includes a refrigerant passage which allows refrigerant to flow therethrough, as part of the refrigerant circuit 110, a water passage which allows water to flow therethrough as part of the water circuit 210, and a thin-plate partition wall which isolates the refrigerant passage and the water passage from each other. The load-side heat exchanger 2 operates as a condenser (heat-transferring device) which heats water during the normal operation, and transfers condensation heat of refrigerant to water, and operates as an evaporator (heat-receiving device) during the defrosting operation.

The pressure-reducing device 6 adjusts the flow rate of refrigerant, and, for example, adjusts the pressure of refrigerant flowing in the load-side heat exchanger 2. The pressure-reducing device 6 in embodiment 1 is an electronic expansion valve whose opening degree can be varied in response to an instruction from a controller 101, which will be described below. For example, a thermosensitive expansion valve (for example, a thermosensitive expansion valve integrated with a solenoid valve) can be used as the pressure-reducing device 6.

The heat-source-side heat exchanger 1 is an air-refrigerant heat exchanger which causes heat exchange to be performed between refrigerant flowing through the refrigerant circuit 110 and outdoor air sent by an outdoor fan (not illustrated) or other devices. The heat-source-side heat exchanger 1 operates as an evaporator (heat-receiving device) during the normal operation, and operates as a condenser (heat-transfer device) during the defrosting operation.

As a first blocking device, a blocking device 77 is provided upstream of the load-side heat exchanger 2 in the flow of the refrigerant in the normal operation. In the flow of the refrigerant in the normal operation, the blocking device 77 is located downstream of the compressor 3 and upstream of the load-side heat exchanger 2 in the refrigerant circuit 110. In the case where the refrigerant flow switching device 4 is provided as in embodiment 1, it is preferable that the blocking device 77 be located downstream of the refrigerant flow switching device 4 and upstream of the load-side heat exchanger 2 in the refrigerant circuit 110 in the flow of the refrigerant in the normal operation. As the blocking device 77, an opening and closing valve (for example, a solenoid valve, a flow control valve or an electronic expansion valve) which is to be controlled by the controller 101 to be described later is used. The blocking device 77 is in an opened state during the operation of the refrigerant circuit 110, which includes the normal operation and the defrosting operation. When the blocking device 77 is made to be in a closed state by the control by the controller 101, the blocking device 77 blocks the flow of the refrigerant.

Furthermore, as a second blocking device, a blocking device 78 is provided downstream of the load-side heat exchanger 2 in the flow of the refrigerant in the normal operation. The blocking device 78 is provided downstream of the load-side heat exchanger 2 and upstream of the heat-source-side heat exchanger 1 in the refrigerant circuit 110 in the flow of the refrigerant in the normal operation. As the blocking device 78, an opening and closing valve (for example, a solenoid valve, a flow-rate control valve or an electronic expansion valve) which is to be controlled by the controller 101 to be described later is used. The blocking device 78 is in the opened state during the operation of the refrigerant circuit 110, which includes the normal operation and the defrosting operation. When set in the closed state by the control by the controller 101, the blocking device 78 blocks the flow of the refrigerant.

In the case where the pressure-reducing device 6 is an electronic expansion valve or a thermosensitive expansion valve integrated with a solenoid valve, the pressure-reducing device 6 can double as the blocking device 78. That is, in the case where the pressure-reducing device 6 is an electronic expansion valve or a thermosensitive expansion valve integrated with a solenoid valve, it is possible to omit the blocking device 78, and also use the pressure-reducing device 6 as a second blocking device. In other words, in the case where the blocking device 78 is an electronic expansion valve or a thermosensitive expansion valve integrated with a solenoid valve, it is possible to omit the pressure-reducing device 6, and cause the blocking device 78 to double as a pressure-reducing device.

For example, a slightly flammable refrigerant such as R1234yf or R1234ze(E) or a highly flammable refrigerant such as R290 or R1270 is used as the refrigerant circulating in the refrigerant circuit 110. Each of these refrigerants may be used as a single refrigerant, or two or more of them may be mixed and used as a mixed refrigerant. Hereinafter, there is a case where a refrigerant having flammability of at least a slightly flammable level (at least 2 L under ASHRAE34 classification, for example) will be referred to as “refrigerant having flammability” or “flammable refrigerant.” Furthermore, an inflammable refrigerant having inflammability (1 under ASHRAE34 classification, for example) such as R4070 or R410A can be used as refrigerant to be circulated in the refrigerant circuit 110. These refrigerants have a higher density than air under atmospheric pressure (when the temperature is room temperature (25 degrees Celsius), for example). Furthermore, refrigerant having toxicity, such as R717 (ammonia), can be used as the refrigerant to be circulated in the refrigerant circuit 110.

The refrigerant circuit 110 including the compressor 3, the refrigerant flow switching device 4, the blocking device 77, the load-side heat exchanger 2, the blocking device 78, the pressure-reducing device 6 and the heat-source-side heat exchanger 1 is provided in the outdoor unit 100.

Furthermore, the controller 101, which performs control manly of an operation of the refrigerant circuit 110 (for example, the compressor 3, the refrigerant flow switching device 4, the blocking devices 77 and 78, the pressure-reducing device 6 and an outdoor fan not illustrated) is provided in the outdoor unit 100. The controller 101 is capable of communicating, via a control line 102, with a controller 201 and an operation unit 202, which will be described later.

An example of the operation of the refrigerant circuit 110 will be described. In FIG. 1, solid arrows indicate the flow direction of refrigerant in the refrigerant circuit 110 in the normal operation. In the normal operation, the refrigerant flow switching device 4 switches refrigerant passages as indicated by the solid arrows, and the refrigerant circuit 110 is configured such that high-temperature, high-pressure refrigerant flows into the load-side heat exchanger 2.

The high-temperature, high-pressure gas refrigerant discharged from the compressor 3 passes through the refrigerant flow switching device 4 and the blocking device 77 being in the opened state, and flows into the refrigerant passage of the load-side heat exchanger 2. In the normal operation, the load-side heat exchanger 2 operates as a condenser. That is, the load-side heat exchanger 2 causes heat exchange to be carried out between refrigerant flowing through the refrigerant passage and water flowing through the water passage, and the condensation heat of the refrigerant is transferred to the water. Thereby, the refrigerant flowing through the refrigerant passage of the load-side heat exchanger 2 condenses and changes into high-pressure liquid refrigerant. Furthermore, the water flowing through the water passage of the load-side heat exchanger 2 is heated by the heat transferred from the refrigerant.

The high-pressure liquid refrigerant condensed at the load-side heat exchanger 2 flows into the pressure-reducing device 6 via the blocking device 78 being in the opened state, and is reduced in pressure to change into low-pressure, two-phase refrigerant. The low-pressure, two-phase refrigerant flows into the heat-source-side heat exchanger 1. In the normal operation, the heat-source-side heat exchanger 1 operates as an evaporator. To be more specific, in the heat-source-side heat exchanger 1, heat exchange is carried out between the refrigerant flowing therein and the outdoor air sent by the outdoor fan, whereby the evaporation heat of the refrigerant is received by the outdoor air. By virtue of this configuration, the refrigerant having flowed into the heat-source-side heat exchanger 1 evaporates and changes into low-pressure gas refrigerant. The low-pressure gas refrigerant is sucked into the compressor 3 via the refrigerant flow switching device 4. The refrigerant sucked into the compressor 3 is compressed and changes into high-temperature, high-pressure gas refrigerant. In the normal operation, the above cycle is continuously repeated.

It will be described by way of example what operation is performed during the defrosting operation. In FIG. 1, broken arrows indicate the flow direction of the refrigerant in the refrigerant circuit 110 in the defrosting operation. In the defrosting operation, the refrigerant flow switching device 4 switches the refrigerant passages as indicated by the broken arrows, whereby the refrigerant circuit 110 is configured such that the high-temperature, high-pressure refrigerant flows into the heat-source-side heat exchanger 1.

The high-temperature, high-pressure gas refrigerant discharged from the compressor 3 flows into the heat-source-side heat exchanger 1 via the refrigerant flow switching device 4. In the defrosting operation, the heat-source-side heat exchanger 1 operates as a condenser. To be more specific, in the heat-source-side heat exchanger 1, the condensation heat of the refrigerant flowing therein is transferred to frost formed on a surface of the heat-source-side heat exchanger 1. By virtue of this configuration, the refrigerant flowing in the heat-source-side heat exchanger 1 condenses and changes into high-pressure liquid refrigerant. Further, the frost formed on the surface of the heat-source-side heat exchanger 1 is melted by the heat transferred from the refrigerant.

The high-pressure liquid refrigerant condensed at the heat-source-side heat exchanger 1 passes through the pressure-reducing device 6, changes into low-pressure, two-phase refrigerant, then passes through the blocking device 78 being in the opened state, and flows into the refrigerant flow passage of the load-side heat exchanger 2. In the defrosting operation, the load-side heat exchanger 2 operates as an evaporator. That is, in the load-side heat exchanger 2, heat exchange is performed between the refrigerant flowing through the refrigerant passage and the water flowing through the water passage, whereby heat is received from the water as the evaporation heat of the refrigerant. By virtue of this configuration, the refrigerant flowing in the refrigerant passage of the load-side heat exchanger 2 evaporates and changes into low-pressure gas refrigerant. The gas refrigerant passes through the blocking device 77 being in the opened state and the refrigerant flow switching device 4, and is then sucked into the compressor 3. The refrigerant sucked into the compressor 3 is compressed and changes into high-temperature, high-pressure gas refrigerant. In the defrosting operation, the above cycle is continuously repeated.

The water circuit 210 will be described. The water circuit 210 of embodiment 1 is a closed circuit which circulates water. In FIG. 1, the flow directions of the water are indicated by outlined arrows. The water circuit 210 is configured such that a water circuit in the outdoor unit 100 and a water circuit in the indoor unit 200 are connected. The water circuit 210 includes a main circuit 220, a branch circuit 221 forming a hot-water supply circuit, and a branch circuit 222 forming part of a heating circuit. The main circuit 220 forms part of the closed circuit. The branch circuits 221 and 222 are connected to the main circuit 220 as branches therefrom. The branch circuits 221 and 222 are disposed in parallel to each other. The branch circuit 221 forms together with the main circuit 220 a closed circuit. The branch circuit 222 forms together with the main circuit 220, a heating apparatus 300, etc., a closed circuit. The heating apparatus 300 is connected to the branch circuit 222. The heating apparatus 300 is provided in the indoor space, and is located separate from the indoor unit 200. As the heating apparatus 300, for example, a radiator or a floor-heating apparatus is used.

With respect to embodiment 1, although water is described as an example of a heat medium which flows in the water circuit 210, another liquid heat medium such as brine can be used as the heat medium.

In the main circuit 220, a strainer 56, a flow switch 57, the load-side heat exchanger 2, a booster heater 54, a pump 53, etc., are connected by water pipes. At intermediate part of the water pipes forming the main circuit 220, a drain outlet 62 is provided to drain water in the water circuit 210. A downstream end of the main circuit 220 is connected to an inflow port of a three-way valve 55 (an example of a branching part) including a single inflow port and two outflow ports. At the three-way valve 55, the branch circuits 221 and 222 branch off from the main circuit 220. An upstream end of the main circuit 220 is connected to a joining part 230. At the joining part 230, the branch circuits 221 and 222 join the main circuit 220. Part of the water circuit 210 which extends from the joining part 230 to the three-way valve 55 via the load-side heat exchanger 2, etc., forms the main circuit 220.

The load-side heat exchanger 2 of the main circuit 220 is provided in the outdoor unit 100. Devices of the main circuit 220 which are other than the load-side heat exchanger 2 are provided in the indoor unit 200. That is, the main circuit 220 of the water circuit 210 is provided to extend between the outdoor unit 100 and the indoor unit 200. Part of the main circuit 220 is provided in the outdoor unit 100, and the remaining part of the main circuit 220 is provided in the indoor unit 200. The outdoor unit 100 and the indoor unit 200 are connected to each other by two connection pipes 211 and 212 which form part of the main circuit 220.

The pump 53 is a device which pressurizes the water in the water circuit 210 to circulate the water in the water circuit 210. The booster heater 54 is a device which further heats the water in the water circuit 210, for example, when the heating capacity of the outdoor unit 100 is insufficient. The three-way valve 55 is a device which changes the flow of the water in the water circuit 210. For example, the three-way valve 55 switches the flow of the water in the main circuit 220 between circulation of the water in the branch circuit 221 and circulation of the water in the branch circuit 222. The strainer 56 is a device which removes scale in the water circuit 210. The flow switch 57 is a device which detects whether the flow rate of the water circulating in the water circuit 210 is higher than or equal to a certain rate. The flow switch 57 can be replaced by a flow-rate sensor.

The booster heater 54 is connected to a pressure relief valve 70 (an example of a pressure protection device). That is, the booster heater 54 serves as connection part of the pressure relief valve 70, which is connected to the water circuit 210. It should be noted that the connection part of the pressure relief valve 70 will be hereinafter occasionally referred to as “connection part”. The pressure relief valve 70 is a protection device which prevents an excessive increase in pressure in the water circuit 210 which accompanies a change in temperature of the water. The pressure relief valve 70 discharges the water to the outside of the water circuit 210 based on the pressure in the water circuit 210. For example, if the internal pressure of the water circuit 210 increases to exceed a pressure control range of an expansion tank 52 (to be described later), the pressure relief valve 70 is opened to discharge the water in the water circuit 210 to the outside of the water circuit 210 from the pressure relief valve 70. The pressure relief valve 70 is provided at the indoor unit 200 in order to effect pressure protection in the water circuit 210 in the indoor unit 200.

A housing of the booster heater 54 is connected to one of ends of a pipe 72 forming a water passage branching off from the main circuit 220. To the other end of the pipe 72, the pressure relief valve 70 is attached. That is, the pressure relief valve 70 is connected to the booster heater 54 by the pipe 72. In the main circuit 220, the temperature of water in the booster heater 54 is the highest. Therefore, the booster heater 54 is most suitable as the connection part to which the pressure relief valve 70 is connected. Further, in the case where the pressure relief valve 70 is connected to the branch circuits 221 and 222, at the branch circuits 221 and 222, respective pressure relief valves 70 need to be provided. In embodiment 1, since the pressure relief valve 70 is connected to the main circuit 220, it suffices to provide a single pressure relief valve 70.

At an intermediate part of the pipe 72, a branching part 72 a is provided. The branching part 72 a is connected to one of ends of a pipe 75. The other end of the pipe 75 is connected to the expansion tank 52. That is, the expansion tank 52 is connected to the booster heater 54 by the pipes 75 and 72. The expansion tank 52 is a device which controls the change of the internal pressure of the water circuit 210, which accompanies the change of the temperature of the water, such that the change of the internal pressure of the water circuit 21 falls within a certain range.

The main circuit 220 includes a refrigerant leakage detecting device 98. The refrigerant leakage detecting device 98 is connected between the load-side heat exchanger 2 and the booster heater 54 (the connection part) in the main circuit 220. The refrigerant leakage detecting device 98 is a device which detects leakage of refrigerant from the refrigerant circuit 110 into the water circuit 210. If refrigerant leaks from the refrigerant circuit 110 into the water circuit 210, the internal pressure of the water circuit 210 raises. Therefore, the refrigerant leakage detecting device 98 can detect the leakage of the refrigerant into the water circuit 210 based on the internal pressure of the water circuit 210 (the value of the pressure or the variation of the pressure thereof which is made with the passage of time). As the refrigerant leakage detecting device 98, for example, a pressure sensor or a pressure switch (high-pressure switch) which detects the internal pressure of the water circuit 210 is used. For example, the pressure switch may adopt an electric system or a mechanical system using a diaphragm. The refrigerant leakage detecting device 98 outputs a detection signal to the controller 101.

In embodiment 1, the blocking devices 77 and 78 and the refrigerant leakage detecting device 98 are all provided in the outdoor unit 100. Therefore, the blocking devices 77 and 78 and the refrigerant leakage detecting device 98 can be connected to the controller 101 by a control line in the outdoor unit 100, thus reducing the cost. Furthermore, control of the blocking devices 77 and 78 based on a detection signal from the refrigerant leakage detecting device 98 (which will be described later) can be achieved in the outdoor unit 100 solely. Therefore, the versatility of the outdoor unit 100 is increased, and the flexibility in combination of the outdoor unit 100 and various indoor units is improved. In a configuration in which the refrigerant leakage detecting device 98 outputs a contact signal when leakage of refrigerant occurs, the refrigerant leakage detecting device 98 and the blocking devices 77 and 78 may be directly connected without being connected to the controller 101.

The branch circuit 221 forming the hot-water supply circuit is provided in the indoor unit 200. An upstream end of the branch circuit 221 is connected to one of the outflow ports of the three-way valve 55. A downstream end of the branch circuit 221 is connected to the joining part 230. The branch circuit 221 includes a coil 61. The coil 61 is located in a hot-water storage tank 51 which stores water therein. The coil 61 is a heating unit which heats the water stored in the hot-water storage tank 51 through heat exchange with water (hot water) circulating in the branch circuit 221 of the water circuit 210. Furthermore, the hot-water storage tank 51 includes an immersion heater 60 provided therein. The immersion heater 60 is a heating unit which further heats the water stored in the hot-water storage tank 51.

To an upper part of the interior of the hot-water storage tank 51, a sanitary circuit-side pipe 81 a (for example, a hot-water supply pipe), which is to be connected to, for example, a shower, is connected. To a lower part of the interior of the hot-water storage tank 51, a sanitary circuit-side pipe 81 b (for example, a supply water pipe) is connected. At a lower part of the hot-water storage tank 51, a drain outlet 63 is provided to drain the water in the hot-water storage tank 51. The hot-water storage tank 51 is covered by a heat insulating material (not illustrated) to prevent reduction of the temperature of the water in the hot-water storage tank 51, which would be caused by heat transfer to the outside of the hot-water storage tank 51. As the heat insulating material, for example, felt, Thinsulate (registered trademark), or vacuum insulation panel (VIP) is applied.

The branch circuit 222 forming part of the heating circuit is provided in the indoor unit 200. The branch circuit 222 includes a supply pipe 222 a and a return pipe 222 b. An upstream end of the supply pipe 222 a is connected to the other outflow port of the three-way valve 55. A downstream end of the supply pipe 222 a and an upstream end of the return pipe 222 b and an upstream end of the return pipe 222 b are connected to a heating-circuit-side pipe 82 a and a heating-circuit-side pipe 82 b, respectively. A downstream end of the return pipe 222 b is connected to the joining part 230. Thereby, the supply pipe 222 a and the return pipe 222 b are connected to the heating apparatus 300 by the heating-circuit-side pipe 82 a and the heating-circuit-side pipe 82 b, respectively. The heating-circuit-side pipes 82 a and 82 b and the heating apparatus 300 are disposed in the indoor space and outside the indoor unit 200. The branch circuit 222 forms together with the heating-circuit-side pipes 82 a and 82 b and the heating apparatus 300, the heating circuit.

The heating-circuit-side pipe 82 a is connected to a pressure relief valve 301. The pressure relief valve 301 is a protection device which prevents an excessive increase in the internal pressure of the water circuit 210, and has the same structure as or a similar structure to the structure of, for example, the pressure relief valve 70. For example, if the internal pressure of the heating-circuit-side pipe 82 a exceeds a set pressure, the pressure relief valve 301 is opened to discharge water in the heating-circuit-side pipe 82 a to the outside of the heating-circuit-side pipe 82 a from the pressure relief valve 301. The pressure relief valve 301 is provided in the indoor space and outside the indoor unit 200.

The heating apparatus 300, the heating-circuit-side pipes 82 a and 82 b and the pressure relief valve 301 in embodiment 1 are not part of the heat-pump hot-water supply heating apparatus 1000, but are equipment to be installed by a technician in the actual place in accordance with the circumstances of each of properties. For example, in existing equipment using a boiler as a heat source apparatus of the heating apparatus 300, there is a case where the heat source apparatus is updated, that is, it is replaced with the heat-pump hot-water supply heating apparatus 1000.

In such a case, the heating apparatus 300, the heating-circuit-side pipes 82 a and 82 b, and the pressure relief valve 301 continue to be used, unless they cause any particular inconvenience. Therefore, it is preferable that the heat-pump hot-water supply heating apparatus 1000 be connectable to variable kinds of equipment regardless of whether the pressure relief valve 301 is provided or not.

The indoor unit 200 is provided with the controller 201 which performs control mainly of the operation of the water circuit 210 (for example, the pump 53, the booster heater 54 and the three-way valve 55). The controller 201 includes a microcomputer provided with a CPU, a ROM, a RAM, an I/O port, etc. The controller 201 can mutually communicate with the controller 101 and the operation unit 202.

The operation unit 202 is configured to allow a user to operate the heat-pump hot-water supply heating apparatus 1000, and to make various settings. In embodiment 1, the operation unit 202 includes a display unit 203 as a notifying unit which indicates information. The display unit 203 is capable of displaying various information such as the state of the heat-pump hot-water supply heating apparatus 1000. The operation unit 202 is provided at, for example, a surface of a housing of the indoor unit 200.

Next, it will be described what operation is performed if the partition wall isolating the refrigerant passage and the water passage from each other is broken in the load-side heat exchanger 2. The load-side heat exchanger 2 operates as an evaporator in the defrosting operation. Therefore, the partition wall of the load-side heat exchanger 2 may be broken by, for example, freezing of water which occurs particularly in the defrosting operation. In general, the pressure of refrigerant flowing in the refrigerant passage of the load-side heat exchanger 2 is higher than the pressure of water flowing in the water passage of the load-side heat exchanger 2 in either the normal operation or the defrosting operation. Therefore, if the partition wall of the load-side heat exchanger 2 is broken, the refrigerant in the refrigerant passage flows out into the water passage and mixes with the water in the water passage in either the normal operation or the defrosting operation. At this time, the pressure of the refrigerant mixing with the water is reduced, and the refrigerant thus gasifies. Further, since the refrigerant the pressure of which is higher than that of the water mixes into the water, the internal pressure of the water circuit 210 is raised.

The refrigerant mixing with the water of the water circuit 210 in the load-side heat exchanger 2 flows not only in a direction along the normal flow of water (that is, a direction from the load-side heat exchanger 2 toward the booster heater 54), but in an opposite direction to the direction of a normal flow of water (that is, a direction from the load-side heat exchanger 2 toward the joining part 230), because of the difference in pressure between the refrigerant and water. In the case where the main circuit 220 of the water circuit 210 is provided with the pressure relief valve 70 as in embodiment 1, the refrigerant mixing with the water can be discharged together with the water into the indoor space from the pressure relief valve 70. Furthermore, in the case where the heating-circuit-side pipe 82 a or 82 b is provided with the pressure relief valve 301 as in embodiment 1, the refrigerant mixing with the water can be discharged together with the water into the indoor space from the pressure relief valve 301. That is, the pressure relief valves 70 and 301 both operate as valves from which the refrigerant mixing with the water in the water circuit 210 is discharged to the outside of the water circuit 210. If the refrigerant has flammability, when the refrigerant is discharged from the pressure relief valve 70 or 301 into the indoor space, there is a risk that a flammable concentration region will be provided in the indoor space.

In embodiment 1, in the case where leakage of refrigerant to the water circuit 210 is detected based on a detection signal from the refrigerant leakage detecting device 98, the controller 101 stops the compressor 3 and causes the blocking devices 77 and 78 to be set in the closed state. Thereby, the flow of the refrigerant in the refrigerant circuit 110 is blocked by the blocking devices 77 and 78 at two positions which precedes and succeeds the load-side heat exchanger 2. That is, with respect to the flow of refrigerant, the load-side heat exchanger 2 is isolated from the refrigerant circuit 110. Therefore, the amount of refrigerant leaking to the water circuit 210 in the load-side heat exchanger 2 can be reduced to an amount less than or equal to the amount of refrigerant existing in the load-side heat exchanger 2. Thus, in embodiment 1, it is possible to reduce leakage of refrigerant into the indoor space through the pressure relief valves 70 and 301.

FIG. 2 is a circuit diagram illustrating a schematic configuration of a heat-pump using apparatus according to a modification of embodiment 1. As illustrated in FIG. 2, the configuration of this modification is different from the configuration as illustrated in FIG. 1 on the point that the load-side heat exchanger 2 is provided in the indoor unit 200. The refrigerant circuit 110 is provided to extend between the outdoor unit 100 and the indoor unit 200. Part of the refrigerant circuit 110 is provided in the outdoor unit 100, and the remaining part of the refrigerant circuit 110 is provided in the indoor unit 200. The outdoor unit 100 and the indoor unit 200 are connected to each other by two connection pipes 111 and 112 which form part of the refrigerant circuit 110. Also in this modification, the same advantages as or similar advantages to those of the configuration as illustrated in FIG. 1 can be obtained. Furthermore, in the modification, the blocking devices 77 and 78 and the refrigerant leakage detecting device 98 are all provided in the indoor unit 200. The refrigerant leakage detecting device 98 outputs a detection signal to the controller 201, and the blocking devices 77 and 78 are controlled by the controller 201. Thereby, the blocking devices 77 and 78 and the refrigerant leakage detecting device 98 can be connected to the controller 201 by a control line in the indoor unit 200. Thus, the cost can be reduced. Furthermore, control of the blocking devices 77 and 78 based on the detection signal from the refrigerant leakage detecting device 98 can be achieved in the indoor unit 200. Therefore, the versatility of the indoor unit 200 is increased, and the flexibility in combination of the indoor unit 200 and various outdoor units is improved.

The position of the refrigerant leakage detecting device 98 provided will be described. FIG. 3 is an explanatory diagram illustrating examples of the position of the refrigerant leakage detecting device 98 in the heat-pump using apparatus according to embodiment 1. FIG. 3 illustrates five positions A to E as examples of the position of the refrigerant leakage detecting device 98. In the case where the refrigerant leakage detecting device 98 is provided at the position A or B, it is connected to the pipe 72. That is, it is connected to the main circuit 220 by the booster heater 54 (connection part), as well as the pressure relief valve 70. In such a case, the refrigerant leakage detecting device 98 can reliably detect leakage of the refrigerant before the refrigerant leaking into the water circuit 210 in the load-side heat exchanger 2 is discharged from the pressure relief valve 70. When the leakage of the refrigerant into the water circuit 210 is detected by the refrigerant leakage detecting device 98, the flow of the refrigerant in the refrigerant circuit 110 is immediately blocked by the blocking devices 77 and 78 at two positions which precedes and succeeds the load-side heat exchanger 2. It is therefore possible to reduce the amount of refrigerant leaking into the indoor space from the pressure relief valve 70 to the minimum. The same advantage as described above or a similar advantage to the advantage as described above can be also obtained in the case where the refrigerant leakage detecting device 98 is connected to the load-side heat exchanger 2 or between the load-side heat exchanger 2 and the booster heater 54 in the main circuit 220.

In the case where the refrigerant leakage detecting device 98 is provided at the position C or D, it is connected between the booster heater 54 (connection part) and the three-way valve 55 in the main circuit 220. In this case, the refrigerant may be discharged from the pressure relief valve 70 before the refrigerant leakage detecting device 98 detects the leakage of the refrigerant. However, as described above, when the leakage of the refrigerant into the water circuit 210 is detected, the flow of the refrigerant in the refrigerant circuit 110 is immediately blocked at two positions which precedes and succeeds the load-side heat exchanger 2. It is therefore possible to reduce the amount of refrigerant leaking from the pressure relief valve 70 into the indoor space to the minimum.

In the case where the refrigerant leakage detecting device 98 is provided at the position E, it is connected between the load-side heat exchanger 2 and the joining part 230 in the main circuit 220. In this case, the refrigerant leakage detecting device 98 can reliably detect leakage of the refrigerant before the refrigerant leaking into the water circuit 210 is discharged from the pressure relief valve 301 provided outside the indoor unit 200. When the leakage of the refrigerant into the water circuit 210 is detected by the refrigerant leakage detecting device 98, the flow of the refrigerant in the refrigerant circuit 110 is immediately blocked by the blocking devices 77 and 78 at two positions which precedes and succeeds the load-side heat exchanger 2. Therefore, it is possible to reduce the amount of refrigerant leaking from the pressure relief valve 301 into the indoor space to the minimum.

In all the configurations as illustrated in FIGS. 1 to 3, the refrigerant leakage detecting device 98 is connected to the main circuit 220, not to a branch circuit (for example, the heating-circuit-side pipes 82 a and 82 b and the heating apparatus 300) installed by a technician in the actual place. Thus, attachment of the refrigerant leakage detecting device 98 and connection between the refrigerant leakage detecting device 98 and the controller 201 can be carried out by a manufacturer of the indoor unit 200. It is therefore possible to avoid human errors such as a failure to attach the refrigerant leakage detecting device 98 and a failure to connect the refrigerant leakage detecting device 98 to the controller 201.

Next, the positions of the blocking devices 77 and 78 will be described. The blocking devices 77 and 78 are arranged in the refrigerant circuit 110, with the load-side heat exchanger 2 interposed between the blocking devices 77 and 78. In the refrigerant circuit 110, the smaller the capacity of a section which extends from the blocking device 77 to the blocking device 78 through the load-side heat exchanger 2, the smaller the amount of leakage of refrigerant through the pressure relief valve 70 or the pressure relief valve 301, that is, the amount of the leakage of the refrigerant can be further reduced. Therefore, preferably, devices having a large capacity, such as the compressor 3 and the heat-source-side heat exchanger 1, should not be provided in the above section. That is, it is preferable that the blocking device 77 be provided upstream of the load-side heat exchanger 2 and downstream of the compressor 3 in the flow of refrigerant during the normal operation. In the case where the refrigerant flow switching device 4 is provided in the refrigerant circuit 110 as in embodiment 1, it is preferable that the blocking device 77 be provided upstream of the load-side heat exchanger 2 and downstream of the refrigerant flow switching device 4 in the flow of refrigerant during the normal operation. Furthermore, it is preferable that the blocking device 78 be provided downstream of the load-side heat exchanger 2 and upstream of the heat-source-side heat exchanger 1 in the flow of refrigerant during the normal operation.

As described above, the heat-pump hot-water supply heating apparatus 1000 (an example of a heat-pump using apparatus) according to embodiment 1 includes the refrigerant circuit 110 which circulates refrigerant, the water circuit 210 (an example of a heat medium circuit) which allows water (an example of a heat medium) to flow through the water circuit 210, and the load-side heat exchanger 2 (an example of a heat exchanger) which causes heat exchange to be performed between the refrigerant and the water. The water circuit 210 includes the main circuit 220 which extends through the load-side heat exchanger 2. The main circuit 220 includes the three-way valve 55 (an example of branching part) which is provided at a downstream end of the main circuit 220, and is connected to the plurality of branch circuits 221 and 222 which branch off from the main circuit 220, and the joining part 230 which is provided at an upstream end of the main circuit 220, and is connected to the plurality of branch circuits 221 and 222 which join the main circuit 220. To the main circuit 220, the pressure relief valve 70 (an example of a pressure protection device 70) and the refrigerant leakage detecting device 98 are connected. The pressure relief valve 70 causes water to flow out of the water circuit 210 based on the internal pressure of the water circuit 210. The refrigerant leakage detecting device 98 detects leakage of refrigerant from the refrigerant circuit 110 into the water circuit 210. In the refrigerant circuit 110, the blocking device 77 (an example of a first blocking device) and the blocking device 78 (an example of a second blocking device) are provided, with the load-side heat exchanger 2 interposed between the blocking devices 77 and 78.

In this configuration, even if refrigerant leaks to the water circuit 210, the flow of the refrigerant in the refrigerant circuit 110 can be blocked by the blocking devices 77 and 78 at two positions which precedes and succeeds the load-side heat exchanger. It is therefore possible to reduce leakage of refrigerant from the pressure relief valve 70 into indoor space. Furthermore, the pressure relief valve 301 may be provided in an on-site installed circuit (for example, the heating-circuit-side pipes 82 a and 82 b) that is connected to the water circuit 210 of the indoor unit 200 at a position which precedes the three-way valve 55 or the joining part 230 as viewed from the main circuit 220 side. In the above configuration, even if the pressure relief valve 301 is provided in the on-site installed circuit, it is possible to reduce leakage of refrigerant from the pressure relief valve 301 into the indoor space.

In the heat-pump hot-water supply heating apparatus 1000 according to embodiment 1, the blocking devices 77 and 78 are opening and closing valves which are closed when leakage of refrigerant to the water circuit 210 is detected. In this configuration, if refrigerant leaks to the water circuit 210, the flow of refrigerant in the refrigerant circuit 110 can be immediately blocked.

In the heat-pump hot-water supply heating apparatus 1000 according to embodiment 1, the pressure relief valve 70 is connected to the booster heater 54 (an example of the connection part) which is located between the load-side heat exchanger 2 and one of the three-way valve 55 and the joining part 230 (which is the three-way valve 55 in this embodiment) in the main circuit 220. The refrigerant leakage detecting device 98 is connected to the remaining one of the three-way valve 55 and the joining part 230 (which is the joining part 230 in this embodiment), or between the above remaining one (the joining part 230 in this embodiment) and the booster heater 54 (the example of the connection part), or the booster heater 54 (the example of the connection part). In this configuration, before refrigerant having leaked to the water circuit 210 flows into the indoor space, the leakage of the refrigerant can be reliably detected.

In the heat-pump hot-water supply heating apparatus 1000 according to embodiment 1, the refrigerant leakage detecting device 98 detects leakage of refrigerant to the water circuit 210 based on the internal pressure of the water circuit 210. In this configuration, leakage of refrigerant can be reliably detected.

In the heat-pump hot-water supply heating apparatus 1000 according to embodiment 1, the blocking device 77 is provided between the compressor 3 and the load-side heat exchanger 2 in the refrigerant circuit 110, and the blocking device 78 is provided between the load-side heat exchanger 2 and the heat-source-side heat exchanger 1 in the refrigerant circuit 110. That is, in the flow of refrigerant in the refrigerant circuit 110 during a heating operation (a normal operation in this embodiment), the blocking device 77 is located downstream of the compressor 3 and upstream of the load-side heat exchanger 2, and the blocking device 78 is located downstream of the load-side heat exchanger 2 and upstream of the heat-source-side heat exchanger 1. In this configuration, devices having a large capacity such as the compressor 3 and the heat-source-side heat exchanger 1 are not located in a section which extends from the blocking device 77 to the blocking device 78 through the load-side heat exchanger 2. Thus, the amount of leakage of refrigerant from the pressure relief valve 70 or the pressure relief valve 301 can be reduced.

In the heat-pump hot-water supply heating apparatus 1000 according to embodiment 1, the blocking device 78 operates as a pressure-reducing device in the refrigerant circuit 110. In this configuration, the number of components in the heat-pump hot-water supply heating apparatus 1000 can be reduced.

The heat-pump hot-water supply heating apparatus 1000 according to embodiment 1 further includes the outdoor unit 100 which accommodates the refrigerant circuit 110, part of the water circuit 210, and the load-side heat exchanger 2, and the indoor unit 200 which accommodates the remaining part of the water circuit 210. The outdoor unit 100 accommodates the blocking devices 77 and 78 and the refrigerant leakage detecting device 98. In this configuration, in the outdoor unit 100, the controller 101 can be connected to each of the blocking devices 77 and 78 and the refrigerant leakage detecting device 98. Thus, the cost can be reduced. Furthermore, in this configuration, the versatility of the outdoor unit 100 can be increased, and the flexibility in combination of the outdoor unit 100 and various indoor units can be improved.

The heat-pump hot-water supply heating apparatus 1000 according to embodiment 1 further includes the outdoor unit 100 which accommodates part of the refrigerant circuit 110 and the indoor unit 200 which accommodates the remaining part of the refrigerant circuit 110, the water circuit 210 and the load-side heat exchanger 2. The indoor unit 200 accommodates the blocking devices 77 and 78 and the refrigerant leakage detecting device 98. In this configuration, in the indoor unit 200, the controller 201 can be connected to the blocking devices 77 and 78 and the refrigerant leakage detecting device 98. Thus, the cost can be reduced. Furthermore, in this configuration, the versatility of the indoor unit 200 can be increased, and the flexibility in combination of the indoor unit 200 and various output units can be improved.

In the heat-pump hot-water supply heating apparatus 1000 according to embodiment 1, as the refrigerant, flammable refrigerant or toxic refrigerant may be used.

Embodiment 2

A heat-pump using apparatus according to embodiment 2 of the present invention will be explained. FIG. 4 is a circuit diagram illustrating a schematic configuration of the heat-pump using apparatus according to embodiment 2. In FIG. 4, a configuration of the indoor unit 200 is primarily illustrated. Components which having the same functions and operations as those in embodiment 1 will be denoted by the same reference signs, and their descriptions will be omitted. As illustrated in FIG. 4, in embodiment 2, a boiler circuit 240 which heats water stored in the hot water storage tank 51 is provided outside the hot water storage tank 51. The boiler circuit 240 includes a water flow passage which connects a lower portion and an upper portion of the hot water storage tank 51. The boiler circuit 240 includes a boiler pump 241 and a boiler heat exchanger 242 which causes heat exchange to be performed between water flowing in the boiler circuit 240 and water flowing in the branch circuit 221. When the boiler pump 241 operates, water in the lower portion of the hot water storage tank 51 flows into the boiler circuit 240. The water having flowed into the boiler circuit 240 is heated by heat exchange at the boiler heat exchanger 242, and returns to the upper portion of the hot water storage tank 51. Also in embodiment 2, the same advantages as or similar advantages to those in embodiment 1 can be obtained.

The present invention is not limited to the above embodiments, and various modifications thereof can be made.

For example, with respect to the above embodiments, the plate-type heat exchanger is described above as an example of the load-side heat exchanger 2. However, a heat exchanger other than the plate-type heat exchanger such as a double-pipe heat exchanger may be used as the load-side heat exchanger 2 as long as the heat exchanger causes heat exchange to be performed between refrigerant and a heat medium.

Furthermore, with respect to the above embodiments, the heat-pump hot-water supply heating apparatus 1000 is described above as an example of a heat-pump using apparatus. However, the present invention is also applicable to other types of heat-pump using apparatus such as a chiller.

Furthermore, with respect to the above embodiments, the indoor unit 200 provided with the hot water storage tank 51 is described above as an example. However, the hot water storage tank may be provided separate from the indoor unit 200.

The embodiments and modifications described above can be variously combined when they are put to practical use.

Reference Signs List

1 heat-source-side heat exchanger 2 load-side heat exchanger 3 compressor 4 refrigerant flow switching device 6 pressure-reducing device 51 hot water storage tank 52 expansion tank 53 pump 54 booster heater 55 three-way valve 56 strainer 57 flow switch 60 immersion heater 61 coil 62, 63 drain outlet pressure relief valve 72 pipe 72 a branching part pipe 77, 78 blocking device 81 a, 81 b sanitary-circuit-side pipe 82 a, 82 b heating-circuit-side pipe 98 refrigerant leakage detecting device 100 outdoor unit 101 controller 102 control line 110 refrigerant circuit 111, 112 connection pipe 200 indoor unit 201 controller 202 operation unit 203 display unit 210 water circuit 211, 212 connection pipe 220 main circuit 221, 222 branch circuit 222 a supply pipe 222 b return pipe 230 joining part 240 boiler circuit 241 boiler pump 242 boiler heat exchanger 300 heating apparatus 301 pressure relief valve 1000 heat-pump hot-water supply heating apparatus 

1. A heat-pump using apparatus comprising: a refrigerant circuit configured to circulate refrigerant; a heat medium circuit configured to cause a heat medium to flow in the heat medium circuit; and a heat exchanger configured to cause heat exchange to be performed between the refrigerant and the heat medium, the heat medium circuit including a main circuit extending via the heat exchanger, the main circuit including a branching part located at a downstream end of the main circuit, and connected to those portions of a plurality of branch circuits which branch off from the main circuit, and a joining part located at an upstream end of the main circuit, and connected to those portions of the plurality of branch circuits which join the main circuit, the main circuit being provided as a circuit to which a pressure protection device and a refrigerant leakage detecting device are connected, the refrigerant circuit including a first blocking device and a second blocking device between which the heat exchanger is located, the pressure protection device being connected to a connection part located between the heat exchanger and one of the branching part and the joining part in the main circuit, the refrigerant leakage detecting device being connected to the other of the branching part and the joining part, or between the connection part and the other of the branching part and the joining part, or to the connection part, in the main circuit.
 2. The heat-pump using apparatus of claim 1, wherein the first blocking device and the second blocking device are opening and closing valves which are closed when leakage of the refrigerant to the heat medium circuit is detected.
 3. (canceled)
 4. The heat-pump using apparatus of claim 1, wherein the refrigerant leakage detecting device detects leakage of the refrigerant to the heat medium circuit based on an internal pressure of the heat medium circuit.
 5. The heat-pump using apparatus of claim 1, wherein the first blocking device is provided between a compressor in the refrigerant circuit and the heat exchanger, and wherein the second blocking device is provided between the heat exchanger and a heat-source-side heat exchanger in the refrigerant circuit.
 6. The heat-pump using apparatus of claim 5, wherein the second blocking device operates as a pressure-reducing device in the refrigerant circuit.
 7. The heat-pump using apparatus of claim 1, further comprising: an outdoor unit accommodating the refrigerant circuit, part of the heat medium circuit and the heat exchanger; and an indoor unit accommodating a remaining part of the heat medium circuit, wherein the outdoor unit further accommodates the first blocking device, the second blocking device and the refrigerant leakage detecting device.
 8. The heat-pump using apparatus of claim 1, further comprising: an outdoor unit accommodating part of the refrigerant circuit; and an indoor unit accommodating a remaining part of the refrigerant circuit, the heat medium circuit and the heat exchanger, wherein the indoor unit further accommodates the first blocking device, the second blocking device and the refrigerant leakage detecting device.
 9. The heat-pump using apparatus of claim 1, wherein the refrigerant is flammable refrigerant or toxic refrigerant. 